1. Field
The present disclosure relates generally to manufacturing parts and, in particular, to a method and apparatus for forming holes. Still more particularly, the present disclosure relates to a method and apparatus for increasing the size of an existing hole.
2. Background
In manufacturing parts, holes may be drilled into parts. The holes may be used to install fasteners to connect and/or attach parts to each other. In some cases, a hole may not extend all the way through a part and may be used to receive a bar, a tab, or some other suitable feature on another part.
Holes may be formed in a number of parts using a drill with a drill bit to form a hole in the part. A hole may be formed using multiple steps, depending on the precision needed for the hole. In forming a hole, an initial hole may be drilled. The initial hole may be referred to as a pilot hole. This initial hole may serve as a guide for a larger hole. The initial hole may be enlarged through a process that may be referred to as boring. Boring may be a process of enlarging a hole that has already been drilled and/or cast. Boring may be used to obtain greater accuracy for a diameter of a hole. Boring also may be used to cut and/or form a tapered hole.
A boring process may be carried out using a number of different types of power tools. For example, without limitation, a boring process may be performed using a drill, a lathe, or a boring mill.
A boring bar may be used with the power tool to bore out the hole. In boring a hole, a boring bar may be used to increase the size of the initial hole. A boring bar may be an elongate member having a number of cutting elements.
One type of boring bar may include a cartridge that may be used in the boring bar. The cartridge may have a number of cutting elements. The cartridge may be inserted into a slot in the boring bar.
One type of cartridge used with a boring bar may be a fixed cartridge in which the cartridge may be secured to the boring bar. The fixed cartridge may not require the surface of the hole to be perpendicular with the center line of the hole. This type of cartridge also may be referred to as a Davis-style cartridge.
Another type of cartridge may be a floating cartridge. With a floating cartridge, the cartridge may be allowed some movement within the hole during a boring operation. This movement may allow the cutting element in the cartridge to self center itself in the hole during the boring operation. This type of cartridge may require the surface of the hole to be substantially perpendicular to the centerline of the hole. This floating type of cartridge may also be referred to as a Muskegon-style cartridge.
With the fixed cartridge, the cutters for the cartridge may need to be adjusted with respect to each other and within the cartridge to maintain desired tolerances for boring a hole. For example, a cutting element in a fixed cartridge may need to be set within around plus or minus 0.0005 inches of the opposing cutting element.
This type of adjustment may be very time consuming. Further, adjusting cutting elements may require a set up of a dial and/or digital measurement indicator. Also, with variations in manufacturing, this adjustment of cutting elements may be repeated if the cartridge is removed from the boring bar. Further, these fixed cartridges also may need to be matched to the slot that is present in the boring bar.
With a floating-type cartridge, the amount of adjustment may be reduced as compared to a fixed cartridge. This type of cartridge, however, may be limited in a number of applications because the cartridge may require the surface of the hole to be perpendicular to the centerline of the hole. The floating-type cartridge also may require a precise hole through the center of the boring bar. Depending on the length of the boring bar, this hole may require specialized equipment to form.
When boring holes using cartridges, the expense for boring holes may be increased because of the cost of the cartridges. Further, the cost of manufacturing boring bars for use with a cartridge also may increase with a floating-type cartridge because of the precision through the center of the boring bar that may be needed.
Therefore, it would be advantageous to have a method and apparatus that takes into account one or more of the issues discussed above, as well as possibly other issues.